﻿<p>The element type
<em>IfcWallType</em> defines commonly shared information for
occurrences of walls. The set of shared information may
include:</p>
<ul>
<li>common properties within shared property sets</li>
<li>common material information</li>
<li>common material layer definitions</li>
<li>common shape representations</li>
</ul>

<blockquote class="note">
NOTE&nbsp; It is illegal to share shape representations as representation maps for occurrences of <em>IfcWallStandardcase</em>.
</blockquote>

<p>It is used to define a wall specification (i.e. the specific
product information, that is common to all occurrences of that
product type). Wall types may be exchanged without being already
assigned to occurrences.</p>
<blockquote class="note">NOTE&nbsp; The product representations are defined
as representation maps (at the level of the supertype
<em>IfcTypeProduct</em>, which gets assigned by an element
occurrence instance through the
<em>IfcShapeRepresentation.Item[1]</em> being an
<em>IfcMappedItem</em>.</blockquote>
<p>Occurrences of the <em>IfcWallType</em> within building models
are represented by instances of <em>IfcWallStandardCase</em> if the
<em>IfcWallType</em> has a single associated
<em>IfcMaterialLayerSet</em>; otherwise they are represented by
instances of <em>IfcWall</em>, or <em>IfcWallElementedCase</em>.
Occurrences of the <em>IfcWallType</em> within structural analysis
models are represented by instances of
<em>IfcStructuralSurfaceMember</em>, or its applicable
subtypes.</p>
<blockquote class="history">HISTORY&nbsp; New entity in IFC2x2.</blockquote>
<p class="spec-head">Informal Propositions:</p>
<ol>
<li>The material assignment, if provided using the
<em>IfcRelAssociatesMaterial</em> relationship, shall not reference
the <em>IfcMaterialLayerSetUsage</em>.</li>
</ol>
